Two-step hdpe preform and container with high axial stretch ratio

Abstract

A method for forming a container from a high-density polyethylene preform by one-step or two-step injection stretch blow molding. The method includes inserting the preform in a mold. The preform has a preform axial length. The method further includes blow-molding the preform into the mold to form the container, including stretching the preform to form the container with a container axial length that is 2.5-5 times greater than the preform axial length.

What is claimed is: 
     
         1 . A method for forming a container from a high-density polyethylene preform by injection stretch blow molding, the method comprising:
 inserting the preform in a mold, the preform having a preform axial length; and   blow-molding the preform into the mold to form the container, including stretching the preform to form the container with a container axial length that is 2.5-5 times greater than the preform axial length.   
     
     
         2 . The method of  claim 1 , wherein the injection stretch blow molding is one-step or two-step. 
     
     
         3 . The method of  claim 1 , wherein blow-molding the preform includes stretching the preform to form the container with a container hoop diameter that is 2.9-4.3 times greater than a preform hoop diameter of the preform. 
     
     
         4 . The method of  claim 3 , wherein blow-molding the preform includes stretching the preform to a total planar stretch ratio of 7.2-21.5 times. 
     
     
         5 . The method of  claim 1 , wherein blow-molding the preform includes stretching the preform to form the container with an interior volume of 1 L-2.5 L. 
     
     
         6 . The method of  claim 5 , wherein blow-molding the preform includes stretching the preform to form the container with a weight of 29.5 g-33 g. 
     
     
         7 . The method of  claim 5 , wherein blow-molding the preform includes stretching the preform to form the container with a weight/volume ratio of 13-29 grams/liter. 
     
     
         8 . The method of  claim 1 , wherein the preform has a preform body thickness of 2.5 mm-5.5 mm. 
     
     
         9 . The method of  claim 1 , wherein blow-molding the preform includes stretching the preform to form the container with a container body thickness of 0.006″ to 0.014″. 
     
     
         10 . The method of  claim 1 , wherein blow-molding the preform includes stretching the preform to form the container with a container sidewall thickness that is 16 to 28 times less than a preform sidewall thickness of the preform. 
     
     
         11 . The method of  claim 1 , wherein blow-molding the preform into the mold to form the container includes heating the preform to a temperature of 124° C. to 133° C. 
     
     
         12 . The method of  claim 1 , wherein blow-molding the preform into the mold to form the container includes injecting air into the preform at less than 25 bar to form the container with an interior volume of 1 L-2.5 L. 
     
     
         13 . The method of  claim 1 , further comprising injection molding the preform prior to inserting the preform into the mold. 
     
     
         14 . The method of  claim 1 , wherein the preform is made of high-density polyethylene having a melt flow index of 1.5-2. 
     
     
         15 . The method of  claim 1 , wherein the preform is made of high-density polyethylene having a density of 0.955-0.960 grams/cm 3 . 
     
     
         16 . The method of  claim 1 , wherein the preform is made of high-density polyethylene. 
     
     
         17 . The method of  claim 1 , wherein the preform is made of bimodal high-density polyethylene combining high-molecular-weight (HMW) and low-molecular-weight (LMW) HDPE resins.